1. Technical Field
The present invention relates to a driving force distribution system that transmits torque between right and left driven wheels by selectively operating two electromagnetic clutches and, in particular, to the structures of the electromagnetic clutches.
2. Description of the Related Art
There is a known technique that enhances turning performance where the engine torque can be distributed between right and left driven wheels via a driving force distribution system that includes two clutches, and the torque distributed to the outer turning wheel is increased while decreasing the torque distributed to the inner turning wheel thereby generating a yaw moment in the turning direction. With regard to such a driving force distribution system, one in which the above-mentioned two clutches are formed from electromagnetic clutches has already been proposed by the present applicant (ref. Japanese Patent Application No. 11-293467).
In the above-mentioned electromagnetic clutches, excitation of a coil attracts an armature toward a core so that the attracted armature effects engagement between clutch discs and clutch plates, and when the electromagnetic clutch is in a disengaged state where the coil is not excited, an air gap is formed between the core and the armature. When a vehicle is turning, one of the right and left electromagnetic clutches is engaged. In the above-mentioned arrangement, since the armature of the electromagnetic clutch that is to be engaged is urged in the direction in which it departs from the core due to a centrifugal force accompanying the turn, the air gap increases. As a result, the time lag from exciting the coil to attracting the armature increases, and there is a possibility that the responsiveness of engagement of the electromagnetic clutch might be degraded and that the power consumption of the electromagnetic clutch might increase.
The present invention has been carried out in view of the above-mentioned circumstances, and it is an object of the present invention to counteract the influence of the centrifugal force accompanying the turning of the vehicle on the operation of the electromagnetic clutches in a driving force distribution system that includes two electromagnetic clutches.
In order to achieve the above-mentioned object, there is proposed an electromagnetic clutch structure in a driving force distribution system that includes a first electromagnetic clutch that transmits torque from a right output shaft connected to a right driven wheel to a left output shaft connected to a left driven wheel, and a second electromagnetic clutch that transmits torque from the left output shaft connected to the left driven wheel to the right output shaft connected to the right driven wheel, selective operation of the first and second electromagnetic clutches transmitting torque from the output shaft that is on the inside of a turn to the output shaft that is on the outside of the turn, wherein the first electromagnetic clutch includes an armature placed on the right side of a core housing a coil, and wherein the second electromagnetic clutch includes an armature placed on the left side of the core housing a coil.
In accordance with the above-mentioned arrangement, when a vehicle turns right, the first electromagnetic clutch is engaged so as to assist the turn by transmitting torque from the right driven wheel that is on the inside of the turn to the left driven wheel that is on the outside of the turn. Since the first electromagnetic clutch is provided with the armature on the right side of the core housing the coil, the armature is urged leftward due to a centrifugal force caused by turning right to reduce an air gap, thereby enhancing the responsiveness of engagement of the first electromagnetic clutch as well as reducing the power consumption. When the vehicle turns left, the second electromagnetic clutch is engaged so as to assist the turn by transmitting torque from the left driven wheel that is on the inside of the turn to the right driven wheel that is on the outside of the turn. Since the second electromagnetic clutch is provided with the armature on the left side of the core housing the coil, the armature is urged rightward due to a centrifugal force caused by turning left to reduce an air gap, thereby enhancing the responsiveness of engagement of the second electromagnetic clutch as well as reducing the power consumption.
Furthermore, in accordance with the invention, there is proposed an electromagnetic clutch structure in a driving force distribution system that includes a first electromagnetic clutch that transmits torque from a right output shaft connected to a right driven wheel to a left output shaft connected to a left driven wheel, and a second electromagnetic clutch that transmits torque from the left output shaft connected to the left driven wheel to the right output shaft connected to the right driven wheel, selective operation of the first and second electromagnetic clutches transmitting torque from the output shaft that is on the outside of a turn to the output shaft that is on the inside of the turn, wherein the first electromagnetic clutch includes an armature placed on the left side of a core housing a coil, and wherein the second electromagnetic clutch includes an armature placed on the right side of a core housing a coil.
In accordance with the above-mentioned arrangement, when a vehicle turns right, the second electromagnetic clutch is engaged so as to stabilize the vehicle behavior by transmitting torque from the left driven wheel that is on the outside of the turn to the right driven wheel that is on the inside of the turn. Since the second electromagnetic clutch is provided with the armature on the right side of the core housing the coil, the armature is urged leftward due to a centrifugal force caused by turning right to reduce an air gap, thereby enhancing the responsiveness of engagement of the second electromagnetic clutch as well as reducing the power consumption. When the vehicle turns left, the first electromagnetic clutch is engaged so as to stabilize the vehicle behavior by transmitting torque from the right driven wheel that is on the outside of the turn to the left driven wheel that is on the inside of the turn. Since the first electromagnetic clutch is provided with the armature on the left side of the core housing the coil, the armature is urged rightward due to a centrifugal force caused by turning left to reduce an air gap, thereby enhancing the responsiveness of engagement of the first electromagnetic clutch as well as reducing the power consumption.
The first electromagnetic clutch and the second electromagnetic clutch of the present invention correspond to a right electromagnetic clutch CR and a left electromagnetic clutch CL respectively of the embodiments below.
Modes for carrying out the present invention are described below by reference to embodiments of the present invention shown in the appended drawings.